Image decoloring apparatus and method setting password to access difference of image data read before and after heating

ABSTRACT

An image decoloring apparatus includes a reader configured to read an image on a sheet to acquire image data, a storage section configured to store the image data acquired by the reader, and a first heater configured to heat the sheet. The apparatus further includes a difference extractor configured to extract difference image data based on first image data read from the sheet before it is heated by the first heater and second image data read from the sheet after it is heated by the first heater. The apparatus additionally includes a setting section configured to set a password required to access the difference image data.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of, and claims the benefit ofpriority to, U.S. patent application Ser. No. 16/000,302 filed Jun. 5,2018, to be issued as U.S. Pat. No. 10,334,139 on Jun. 25, 2019, whichin turn claims the benefit of priority from Japanese Patent ApplicationNo. 2017-168464, filed Sep. 1, 2017, the entire contents of all of whichare incorporated herein by reference.

FIELD

Embodiments described herein relate generally to an image decoloringapparatus having a function of extracting and managing characters andfigures written with ink decolored when heated from a sheet.

BACKGROUND

An image decoloring apparatus having an image reading function and animage decoloring function is known.

Before a decoloring process, the image decoloring apparatus reads asheet on which characters and figures (hereinafter, referred to as ahandwritten image) written with decolorable ink decolored when heatedand an image formed with color material decolored at a temperaturedifferent from that of the decolorable ink are printed. Thereafter, theimage on the sheet is decolored, and the sheet after the imagedecoloring is read again. As a result, the image decoloring apparatusacquires image data before and after the image decoloring process. Theimage decoloring apparatus separates image data corresponding to thehandwritten image and image data corresponding to an image other thanthe handwritten image based on the image data acquired before and afterthe image decoloring process.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating an image decoloringapparatus according to a first embodiment;

FIG. 2 is a control block diagram illustrating a hardware configurationof the image decoloring apparatus according to the first embodiment;

FIG. 3 is a functional block diagram of a controller according to thefirst embodiment;

FIG. 4 is a diagram illustrating a sheet on which a handwritten image isformed according to the first embodiment;

FIG. 5 is a diagram illustrating second image data and difference imagedata according to the first embodiment;

FIG. 6 is a diagram illustrating a modification of the difference imagedata and the second image data according to the first embodiment;

FIG. 7 is a diagram illustrating a notification mail for a passwordaccording to the first embodiment;

FIG. 8 is a control flowchart depicting extraction of the differenceimage data by the image decoloring apparatus according to the firstembodiment;

FIG. 9 is a control flowchart depicting generation of third image dataaccording to the first embodiment;

FIG. 10 is a cross-sectional view illustrating an image decoloringapparatus according to a second embodiment; and

FIG. 11 is a control flowchart depicting extraction of difference imagedata by the image decoloring apparatus according to the secondembodiment.

DETAILED DESCRIPTION

In accordance with at least one embodiment, an image decoloringapparatus comprises a reading section configured to read an image on asheet to acquire image data, a storage section configured to store theimage data acquired by the reading section, a first heating sectionconfigured to heat the sheet, a difference extraction section configuredto extract difference image data based on first image data read from thesheet before heated by the first heating section and second image dataread from the sheet after it is heated by the first heating section, anda setting section configured to set a password necessary for the use ofthe difference image data (i.e., the password may be required in orderto access the difference image data).

Hereinafter, embodiments of the present invention will be described withreference to the accompanying drawings.

First Embodiment

An image decoloring apparatus 100 decolors an image formed by adecolorable toner formed on a sheet by applying heat to the sheet. Here,the decolorable toner is formed by containing a decolorable material ina coloring material. The decolorable toner is decolored (including for acase in which an image formed with chromatic colors as well asachromatic colors such as white and black becomes visually invisible)when heated. Similarly, the image decoloring apparatus 100 can decoloran image formed with decolorable ink.

FIG. 1 is a cross-sectional view of the image decoloring apparatus 100according to the first embodiment. The image decoloring apparatus 100has a control panel 10, a sheet feed tray 12, a first conveyance path14, a second conveyance path 16, a reading section (reader) 18, aheating section (heater) 20, and a sheet discharge section (sheetdischarger) 22.

The control panel 10 has a display section (a display) and an operationsection (an operation panel). The display section is, for example, aliquid crystal display or an organic EL (Electro Luminescence) display.The display section displays various information relating to the imagedecoloring apparatus 100. The control panel 10 includes a plurality ofbuttons to receive an operation by a user. The operation section outputsa signal in response to the operation performed by the user to acontroller 30 described later. The display section and the operationsection may be integrally configured as a touch panel.

The sheet feed tray 12 stacks sheets to be reused. The sheet to bereused may be, for example, a sheet on which an image is formed with thedecolorable toner. The sheet may have various sizes such as A3, A4, B5,etc. The sheet feed tray 12 is provided with a pickup roller 12 a, asheet feed roller 12 b, and a separation roller 12 c which is arrangedto face the sheet feed roller. These rollers convey the sheets one byone to the first conveyance path 14.

The first conveyance path 14 extends from the sheet feed tray 12 to thesheet discharge section 22. Along the first conveyance path 14, abifurcating point 24, a junction point 26, a reading section 18 and aplurality of conveyance rollers 19 which are described later areprovided.

The second conveyance path 16 is connected to the first conveyance path14 at the bifurcating point 24 and the junction point 26 provided at theupstream side of the bifurcating point 24 in the first conveyance path14. In other words, the first conveyance path 14 and the secondconveyance path 16 form a circular path. The second conveyance path 16has a plurality of conveyance rollers 19. The bifurcating point 24 has abifurcating member 24 a. The controller 30 conveys the sheet conveyedalong the first conveyance path 14 to the second conveyance path 16 bysetting the bifurcating member 24 a in a driven state. The controller 30conveys the sheet conveyed along the first conveyance path 14 to thesheet discharge section 22 described later by setting the bifurcatingmember 24 a in a non-driven state.

The reading section 18 is arranged between the junction 26 and thebifurcating point 24 along the first conveyance path 14. The readingsection 18 is, for example, a scanner which reads images on both sidesof a target sheet. The image data read by the reading section 18 isstored in a storage section 40 described later. The image data stored inthe storage section 40 may be transmitted to another image formingapparatus or an information processing apparatus such as a PC via anetwork.

The heating section 20 is arranged along the second conveyance path 16.The heating section 20 has a roller pair and a heater, and the rollerpair is heated by the heater. The heating section 20 heats an imageformed with the decolorable ink or the decolorable toner to decolor theimage by applying a certain amount or more of heat to the sheet via theheated roller pair.

The sheet discharge section 22 is arranged at the downstream side of thebifurcating point 24 along the first conveyance path 14. The sheetdischarge section 22 has a sheet discharge roller 22 a and a sheetdischarge tray 22 b. The sheet discharge roller 22 a discharges thesheet conveyed along the first conveyance path 14 to the sheet dischargetray 22 b. The sheet discharge tray 22 b accommodates discharged sheets.

The conveyance path and a decoloring process of the sheet conveyed alongthe first conveyance path 14 and the second conveyance path 16 aredescribed. The sheet fed from the sheet feed tray 12 is conveyed alongthe first conveyance path 14. Thereafter, when the sheet reaches thebifurcating point 24, the sheet is conveyed to the second conveyancepath 16 via the bifurcating member 24 a in the driven state. The sheetconveyed along the second conveyance path 16 is heated by the heatingsection 20, and thus, an image I1 (hereinafter, referred to as a firstimage) formed with the decolorable toner is subjected to the decoloringprocess. Thereafter, the sheet is conveyed to the first conveyance path14 via the junction point 26.

The sheet is conveyed again along the first conveyance path 14 andreaches the bifurcating point 24. The sheet is conveyed along the firstconveyance path 14 via the bifurcating member 24 a in the non-drivenstate and is then conveyed to the sheet discharge tray 22 b.

FIG. 2 is a control block diagram of the image decoloring apparatus 100according to the first embodiment. The image decoloring apparatus 100has a control panel 10, the reading section 18, the heating section 20,the controller 30, the storage section 40, an authentication section 42,a conveyance section 44 and a communication I/F 46. These sections areconnected via a bus 48.

In the following description, an image formed on the sheet before thedecoloring process is referred to as the first image I1, and an imageformed on the sheet after the decoloring process is referred to as asecond image 12. Image data acquired from the first image I1 by thereading section is referred to as first image data D1, and image dataacquired from the second image 12 is referred to as second image dataD2.

The controller 30 has a processor 32 which is a CPU (Central ProcessingUnit) or a MPU (Micro Processing Unit), and a memory 34. The memory 34is, for example, a semiconductor memory, and has a ROM (Read OnlyMemory) 36 that stores various control programs and a RAM (Random AccessMemory) 38 that provides a temporary work area for the processor 32. Thecontroller 30 controls each section of the image decoloring apparatus100 based on various programs stored in the ROM 36. The RAM 38 maytemporarily store the image data read by the reading section 18.

The storage section 40 stores various image data. The various image dataincludes the first image data D1, the second image data D2, differenceimage data B and third image data D3 which are described later. As aresult, when a decolored image is required, the image data correspondingto the image can be acquired.

The storage section 40 may be, for example, a hard disk drive, othermagnetic storage devices, optical storage devices, semiconductor storagedevices such as flash memory or the like, or may be any combinationthereof.

In the storage section 40, a storage area which cannot be accessed fromthe outside in the memory is provided, and it is preferable to store thefirst image data D1 in this storage area. On the other hand, if thesecond image data D2 acquired from the sheet after the decoloringprocess is stored, the storage section 40 stores the image data as datawhich can be browsed or stored with a PC, or can be printed with a MFP(Multi-Function Peripheral) by a user.

The authentication section 42 acquires authentication data relating tothe user. The authentication data is used for specifying the user whoexecutes a job. For example, the authentication section 42 acquires theauthentication data from a PC that sends the job and an ID card heldwhen the operation section is operated. The authentication data may bestored in the storage section 40.

The conveyance section 44 includes a plurality of conveyance rollers 19provided in the first conveyance path 14 and the second conveyance path16, a sheet feed roller, the sheet discharge roller 22 a, and a drivingmotor. These rollers are driven by the driving motor to operate.

The communication I/F 46 is used for connecting with an external device.The communication I/F 46 communicates with the external device on thenetwork through an appropriate wired or wireless communication such asIEEE 802.15, IEEE 802.11, IEEE 802.3, etc., which are Bluetooth®Technology, infrared communication, optical communication, respectively.The communication I/F 46 may further include a USB connection section towhich a connection terminal conforming to the USB standard is connected,a parallel interface, or the like. The controller 30 communicates withthe MFP and other external devices via the communication I/F 46.

FIG. 3 is a functional block diagram illustrating the functions of thecontroller 30. The controller 30 functions as a difference extractionsection (a difference extractor) 50, an image generation section (animage generator) 52, a setting section (a setting input) 54, anacquisition section 56, a determination section 58, a cancel section 60,and an image deletion section 62.

The difference extraction section 50 extracts image data B (hereinafter,referred to as difference image data) of a difference between the imagedata stored in the storage section 40. For example, the image data D1acquired by the reading section 18 from the image I1 on the sheet beforethe decoloring process and the image data D2 acquired by the readingsection 18 from the image 12 on the sheet after the decoloring processare compared with each other. The difference extraction section 50extracts the difference between these image data as the difference imagedata B.

In the present embodiment, a temperature T1 at which the image formed bythe decolorable toner is decolored is higher than a temperature T2 atwhich the image formed by the decolorable ink is decolored. The heatingsection 20 is set at the temperature T2 at which the image by thedecolorable ink is decolored.

For example, if a toner image and a handwritten image A formed with thedecolorable ink are formed on the sheet, the heating section 20 executesthe decoloring process to decolor the handwritten image A. Therefore,only the toner image is formed on the sheet. Therefore, if the imagedata before the decoloring process is compared with the image data afterthe decoloring process, a part of the decolored handwritten image A isextracted as the difference image data B. The controller 30 stores theextracted difference image data B in the storage section 40.

The difference extraction section 50 acquires position information ofthe part corresponding to the difference image data B in the first imagedata D1, and stores the position information in association with each ofthe difference image data B in the storage section 40.

The image generation section 52 generates the third image data D3 basedon the second image data D2 and the difference image data B.Specifically, the third image data D3 is generated by synthesizing thedifference image data B on the second image data D2 based on theposition information associated with the difference image data B.Therefore, the third image data D3 is substantially the same as thefirst image data D1 acquired from the sheet before the decoloringprocess. In order to generate the third image data D3 by the imagegeneration section 52, it is necessary to input a password set in thesetting section 54 described later. The generated third image data D3can be handled freely by being browsed, stored, or printed by the MFP.

The setting section 54 sets the password for the difference image dataB. The password is used when using the difference image data B. Forexample, the password is used to browse the difference image data Bstored in the storage section 40, and to generate the third image 13.The setting section 54 has a password setting table as shown in Table 1.“Using the difference image data B” means that the difference image dataB stored in the storage section 40 is displayed on the display section,or that a composition process is executed with the difference image dataB and the second image data. In other words, “Using the difference imagedata B” means that after the controller 30 stores “the difference imagedata B” in the storage section 40, the difference image data B is readfrom the storage section 40 to be used again.

TABLE 1 Image data Password XXXXXXX.jpg AAAAAAA YYYYYYY.jpg BBBBBBBZZZZZZZ.jpg CCCCCCC

For example, if the difference extraction section 50 extracts thedifference image data B, the setting section 54 registers the differenceimage data B and a newly set password in an associated manner. Thepassword is set by a method such as the user inputting the password intoan input reception section (a receiver) via the control panel 10, forexample. Even if the user does not individually set the password, thecontroller 30 may specify the PC of the user from the information in theID card authenticated when performing the decoloring process, andtransmit the automatically generated password to the PC to set thepassword.

The acquisition section 56 acquires the password from the control panelor the communication I/F. The password acquired here is referred to bythe determination section 58 described later when canceling the passwordset in the setting section 54.

The determination section 58 confirms whether the password set in thesetting section 54 matches with the password acquired by the acquisitionsection 56.

The cancel section 60 cancels the password of the difference image dataB when the determination section 58 determines that the passwordassociated with the difference image data B in the password settingtable matches with the password acquired by the acquisition section 56.

The image deletion section 62 deletes the first image data D1 stored inthe storage section 40 after the image generation section 52 generatesthe difference image data B based on the first image data D1 and thesecond image data D2.

Apart or all of the difference extraction section 50, the imagegeneration section 52, the setting section 54, the acquisition section56, the determination section 58, the cancel section 60, and the imagedeletion section 62 may be realized by an ASIC (Application SpecificIntegrated Circuit) which is the processor 32.

Next, the decoloring process and the extraction of the difference imagedata B in the image decoloring apparatus 100 according to the firstembodiment are described. FIG. 4 is a diagram illustrating a sheet onwhich the handwritten image A is formed with the decolorable ink. On thesheet, the handwritten image A which is formed by the decolorable inkand decolored when heated at a temperature equal to or higher than thedecoloring temperature, and the second image 12 which is not decoloredwhen heated at the temperature equal to or higher than the decoloringtemperature are formed.

First, the controller 30 reads, with the reading section 18, the sheetbefore the heating section 20 executes the decoloring process byheating. The controller 30 stores the acquired first image data D1 inthe storage section 40. The storage section 40 has an area which cannotbe accessed from the outside in the memory, and stores the image data inthis area. Next, the controller 30 reads, with the reading section 18, asheet obtained by heating the handwritten image A by the heating section20 and performing the decoloring process on the handwritten image A. Thecontroller 30 stores the acquired second image data D2 in the storagesection 40.

The difference extraction section 50 compares the first image data D1stored in the storage section 40 with the second image data D2 toacquire the difference image data B. The controller 30 stores theacquired difference image data B in the storage section 40. At thistime, the controller 30 may delete the first image data D1 from the datastored in the storage section 40. As a result, it is possible tosuppress the amount of memory being used, so as to avoid limiting theamount of available memory capacity, due to the storage of the firstimage data D1 in the storage section 40.

FIG. 5 is a diagram illustrating the second image data D2 and thedifference image data B. FIG. 5(a) exemplifies the second image data D2,and FIG. 5(b) illustrates the difference image data B. The second imagedata D2 is the image data of an image formed on the sheet after thedecoloring process at the decoloring temperature by the heating section20. On the other hand, the difference image data B corresponds to theimage data of an image decolored by the decoloring process at thedecoloring temperature by the heating section 20.

The user can access the memory 34 in a main body of the image decoloringapparatus 100 using a PC to browse and store the second image data D2,or to print the second image data D2 with the MFP. Alternatively, theseoperations may be performed from the control panel 10 of the imagedecoloring apparatus 100. On the other hand, in the difference imagedata B, it is possible to set a password unique to the user by thesetting section 54. In that case, if no password is input, thecontroller 30 displays the difference image data B on the displaysection and does not generate the third image data D3 with the imagegeneration section 52. This can increase the confidentiality of thehandwritten image A with high confidentiality.

The setting section 54 may set a password for all the image data or onlyfor the image data having predetermined information in the differenceimage data B extracted by the difference extraction section 50.

For example, FIG. 6 is a diagram illustrating the image data acquiredfrom the sheet on which the handwritten image A is formed with thedecolorable ink. On the sheet, the handwritten image A which is formedwith the decolorable ink and decolored when heated at the temperatureequal to or higher than the decoloring temperature, and the second image12 which is not decolored even when heated at the temperature equal toor higher than the decoloring temperature are formed. For example, inthe handwritten image A, it is assumed that simple information that isallowable to be browsed by persons is formed with black decolorable ink,and confidential information such as personal information is formed withred decolorable ink. The difference extraction section 50 acquires thedifference image data B based on the first image data D1 and the secondimage data D2 acquired by the reading section 18 after executing thedecoloring process by the heating section 20. Here, the difference imagedata B corresponding to the handwritten image A formed with the blackdecolorable ink is referred to as difference image data B1. Thedifference image data B corresponding to the handwritten image A formedwith the red decolorable ink is referred to as difference image data B2.

The setting section 54 sets a password only for the difference imagedata B2 of the difference image data B acquired here. When the imagegeneration section 52 generates new image data based on the second imagedata D2 and the difference image data B1, it is not necessary to inputthe password. On the other hand, when the image generation section 52generates new image data based on the second image data D2 and thedifference image data B2, it is necessary to input the password.

If the reading section 18 is an OCR or the like and can identifycharacters and figures, the controller 30 may determine whether to set apassword in the difference image data B based on the identificationresult.

As a result, it is possible to simply use the handwritten image A withlow confidentiality while increasing the confidentiality of thehandwritten image A with high confidentiality.

FIG. 7 is a diagram illustrating an example of a mail sent by thecontroller 30 to the PC of the user when the difference extractionsection 50 generates the difference image data B. In the mail shown inFIG. 7, a password automatically set by the setting section 54 isrecorded. The image generation section 52 generates the third image dataD3 if the user performs an operation such as inputting the password withthe control panel 10 or inputting the password on the PC.

FIG. 8 is a flowchart depicting an image storage processing by the imagedecoloring apparatus 100. First, if the authentication section 42authenticates an ID card, and the controller 30 acquires a decoloringjob, the controller 30 starts the decoloring process (ACT 100). Thecontroller 30 reads the sheet conveyed along the first conveyance path14 with the reading section 18 to acquire the first image data D1 (ACT101). Thereafter, if the sheet conveyed along the first conveyance path14 reaches the bifurcating point 24, the controller 30 sets thebifurcating member 24 a in the driven state to convey the sheet to thesecond conveyance path 16. The controller 30 executes the decoloringprocess on the sheet conveyed along the second conveyance path 16 withthe heating section 20 (ACT 102). As a result, the handwritten image Aon the sheet is decolored. The controller 30 conveys the sheet subjectedto the decoloring process to the first conveyance path 14 via thejunction point 26. The controller 30 again reads the conveyed sheet withthe reading section 18 to acquire the second image data D2 (ACT 103).Thereafter, the controller 30 discharges the sheet conveyed along thefirst conveyance path 14 to the sheet discharge section 22.

Based on the first image data D1 and the second image data D2 acquiredby the reading section 18, the controller 30 acquires the differenceimage data B with the difference extraction section 50 (ACT 104). If thesetting section 54 does not set the password for the difference imagedata B (No in ACT 105), the controller 30 stores the difference imagedata B in the storage section 40 without setting the password (ACT 106).If the setting section 54 sets the password for the difference imagedata B (Yes in ACT 105), the controller 30 sets the password inassociation with the user ID acquired with the authentication section 42and stores the difference image data B in the storage section 40 (ACT107). The controller 30 deletes the first image data D1 stored in thestorage section 40 with the image deletion section 62 if the differenceimage data B is stored in the storage section 40 (ACT 108). Thecontroller 30 terminates the decoloring process upon completion of theseprocesses.

FIG. 9 is a flowchart depicting generation of the third image data D3according to the present embodiment. If the generation process of thethird image data D3 is received from the PC, the controller 30 startsthe image generation process (ACT 200). The controller 30 determineswhether or not the password is set for the difference image data B usedfor generating the designated image data (ACT 201). If the password isnot set (No in ACT 201), the controller 30 generates the third imagedata D3 based on the second image data D2 and the difference image dataB with the image generation section 52 (ACT 204). In ACT 202, if thepassword is set (Yes in ACT 201), the controller 30 receives an input ofthe password with the acquisition section 56 (ACT 202). If thedetermination section 58 determines that the input password is not acorrect password (No in ACT 202), the controller 30 returns to theprocess in ACT 200. If the determination section 58 determines that theinput password is the correct password (Yes in ACT 202), the cancelsection 60 cancels the password (ACT 203). Thereafter, the controller 30generates the third image data D3 based on the second image data D2 andthe difference image data B with the image generation section 52 (ACT204). Thereafter, the controller 30 outputs the third image data D3 tothe storage section 40 (ACT 205). The controller 30 displays the thirdimage data D3 on a screen of the PC or performs printing (ACT 206).Thereafter, the image generation process is terminated.

As described above, the image decoloring apparatus 100 according to thepresent embodiment acquires the image data of images formed on the sheetbefore and after the decoloring process, sets and stores the passwordsfor the difference image data B of those image data, and in this way,the confidential information can be prevented from being derived fromthe handwritten image A.

Second Embodiment

In an image decoloring apparatus of the second embodiment, by providinga low-temperature decoloring route and a high-temperature decoloringroute, it is possible to acquire the difference image data B from thehandwritten image A even for the sheet on which an image is formed withthe decolorable toner. Below, it is assumed that the second image 12formed with the decolorable toner and the handwritten image A writtenwith the decolorable ink are formed on the sheet.

FIG. 10 is a cross-sectional view of an image decoloring apparatus 200according to the second embodiment. In the following description, thedescription of the same components as the first embodiment is omitted.

The image decoloring apparatus 200 includes the control panel 10, thesheet feed tray 12, the first conveyance path 14, the second conveyancepath 16, a third conveyance path 70, the reading section 18, the firstheating section 20 a, a second heating section (heater) 20 b, and thesheet discharge section 22.

The second conveyance path 16 is connected to the first conveyance path14 at a first bifurcating point 72 and a first junction point 74provided at the upstream side of the first bifurcating point 72 in thefirst conveyance path 14. In other words, the first conveyance path 14and the second conveyance path 16 form a circular path. A plurality ofthe conveyance rollers 19 is provided on the second conveyance path 16.A first bifurcating member 72 a is arranged at the first bifurcatingpoint 72. The controller 30 conveys the sheet conveyed through the firstconveyance path 14 along the second conveyance path 16 by setting thefirst bifurcating member 72 a in the driven state. The controller 30conveys the sheet conveyed along the first conveyance path 14 to thesheet discharge section 22 by setting the first bifurcating member 72 ain the non-driven state.

The third conveyance path 70 is connected to the second conveyance path16 at a second bifurcating point 76 and a second junction point 78 atthe downstream side of the second bifurcating point 76 on the secondconveyance path 16. A plurality of the conveyance rollers 19 is providedon the third conveyance path 70. A second bifurcating member 76 a isarranged at the second bifurcating point 76. The controller 30 conveysthe sheet conveyed along the second conveyance path 16 to the thirdconveyance path 70 by setting the second bifurcating member 76 a in thedriven state. The controller 30 conveys the sheet along the secondconveyance path 16 by setting the second bifurcating member 76 a in thenon-driven state.

The first heating section 20 a is provided on the third conveyance path70. The first heating section 20 a has a roller pair and a heater, whichis the same as the heating section 20 of the first embodiment. In thisway, the sheet is heated and the decoloring process is performed.Hereinafter, a temperature of the first heating section 20 a is definedas a first decoloring temperature.

The second heating section 20 b is provided along the second conveyancepath 16, between the second bifurcating point 76 and the second junctionpoint 78. The second heating section 20 b has a roller pair and aheater, which is the same as the heating section 20 of the firstembodiment. In this way, the sheet is heated and the decoloring processis performed. Hereinafter, a temperature of the second heating section20 b is defined as a second decoloring temperature.

The first decoloring temperature is lower than the second decoloringtemperature. Specifically, the first decoloring temperature is atemperature at which the decolorable ink is decolorable but thedecolorable toner is not decolorable. The second decoloring temperatureis a temperature at which both the decolorable ink and decolorable tonerare decolorable.

Here, the conveyance path of the sheet conveyed along each conveyancepath and the decoloring process are described. The sheet fed from thesheet feed tray 12 is conveyed along the first conveyance path 14.Thereafter, if the sheet reaches the first bifurcating point 72, thesheet is conveyed to the second conveyance path 16 via the firstbifurcating member 72 a in the driven state. If the sheet conveyed alongthe second conveyance path 16 reaches the second bifurcating point 76,the sheet is conveyed to the third conveyance path 70 via the secondbifurcating member 76 a in the driven state, and the decoloring processof the handwritten image A is performed by the first heating section 20a. Thereafter, the sheet is conveyed to the second conveyance path 16via the second junction point 78, and is conveyed to the firstconveyance path 14 via the first junction point 74 after conveyed alongthe second conveyance path 16.

If the sheet is conveyed again along the first conveyance path 14 andreaches the first bifurcating point 72, the sheet is conveyed to thesecond conveyance path 16 via the first bifurcating member 72 a in thedriven state. If the sheet conveyed along the second conveyance path 16reaches the second bifurcating point 76, the sheet is conveyed along thesecond conveyance path 16 by setting the second bifurcating member 76 ain the non-driven state. Thereafter, the decoloring process is performedon the image formed with the decolorable toner on the sheet by thesecond heating section 20 b. In other words, here the second image 12 isdecolorized. Thereafter, the sheet is conveyed to the first conveyancepath 14 via the first junction point 74.

The sheet is conveyed again along the first conveyance path 14. If thesheet is conveyed to the first bifurcating point 72, the sheet isconveyed along the first conveyance path 14 to the sheet discharge tray22 b by setting the first bifurcating point 72 in the non-driven state.

If these decoloring processes are terminated, the difference extractionsection 50 extracts the difference image data B from the first imagedata D1 and the second image data D2 like the first embodiment. Thecontroller 30 stores the second image data D2 and the difference imagedata B in the storage section 40. The controller 30 may set the passwordfor the difference image data B with the setting section 54 and store itin the storage section 40. In that case, the controller 30 notifies theuser of the password by sending a mail or the like as shown in FIG. 7.

FIG. 11 is a flowchart depicting the image storage processing by theimage decoloring apparatus 200 according to the second embodiment.First, if the authentication section 42 recognizes an ID card, thecontroller 30 starts the decoloring process (ACT 300). The controller 30reads the sheet conveyed along the first conveyance path 14 with thereading section 18 to acquire the first image data D1 (ACT 301).Thereafter, the controller 30 sets the first bifurcating member 72 a inthe driven state to convey the sheet to the second conveyance path 16 ifthe sheet conveyed along the first conveyance path 14 reaches the firstbifurcating point 72. Furthermore, if the sheet conveyed along thesecond conveyance path 16 reaches the second bifurcating point 76, thecontroller 30 sets the second bifurcating member 76 a in the drivenstate to convey the sheet to the third conveyance path 70. Thecontroller 30 executes the decoloring process with the first heatingsection 20 a on the sheet conveyed along the third conveyance path 70(ACT 302). In this way, the handwritten image A is decolored. Thecontroller 30 conveys the sheet subjected to the decoloring process tothe second conveyance path 16 via the second junction point 78. Thecontroller 30 conveys the sheet conveyed along the second conveyancepath 16 to the first conveyance path 14 via the first junction point 74.The controller 30 again reads the conveyed sheet in the reading section18 to acquire the second image data D2 (ACT 303). Thereafter, thecontroller 30 sets the first bifurcating member 72 a in the driven stateto convey the sheet to the second conveyance path 16 again if the sheetconveyed along the first conveyance path 14 reaches the firstbifurcating point 72. The controller 30 sets the second bifurcatingmember 76 a in the non-driven state to convey the sheet along the secondconveyance path 16. The controller 30 executes the decoloring processwith the second heating section 20 b on the conveyed sheet (ACT 304). Asa result, the second image 12 formed with the decolorable toner isdecolored. The controller 30 conveys the decolored sheet to the firstconveyance path 14 via the first junction point 74. Thereafter, thecontroller 30 sets the first bifurcating member 72 a in the non-drivenstate and discharges the conveyed sheet to the sheet discharge section22.

The controller 30 extracts the difference image data B based on thefirst image data D1 and the second image data D2 acquired by the readingsection 18 in the difference extraction section 50 (ACT 305). If thesetting section 54 does not set the password for the difference imagedata B (No in ACT 306), the controller 30 stores the difference imagedata B in the storage section 40 without setting the password (ACT 307).If the password is set for the difference image data B by the settingsection 54 (Yes in ACT 306), the controller 30 sets the password basedon the user ID acquired by the authentication section 42 and stores thedifference image data B in the storage section 40 (ACT 308). If thecontroller 30 stores the difference image data B in the storage section40, the controller 30 deletes the first image data D1 stored in thestorage section 40 with the image deletion section 62 (ACT 309). Thecontroller 30 thus completes the series of the decoloring process.

As described above, the image decoloring apparatus of the presentembodiment acquires the difference image data B from the image dataacquired from the sheet before and after the decoloring process, anddecolor both the image formed with the decolorable toner and thehandwritten image A, thereby further enhancing confidentiality.

In at least one embodiment, the image decoloring apparatus is describedas an exemplary implementation, but the present invention is not limitedthereto. For example, the image decoloring apparatus may be an MFPhaving a decoloring function.

As described above, in the image forming apparatus of at least oneembodiment, the handwritten image A written with the decolorable ink canbe extracted from the sheet and can be managed while maintaining highlyconfidentially.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of invention. Indeed, the novel apparatus and methods describedherein may be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the apparatus andmethods described herein may be made without departing from the spiritof the inventions. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the inventions.

What is claimed is:
 1. An image decoloring apparatus, comprising: a reader configured to read an image on a sheet, including an image formed by decolorable ink or decolorable toner, to acquire image data and read the image on the sheet after decoloring the image formed by the decolorable ink or the decolorable toner to acquire image data; a memory configured to store the image data acquired by the reader; a processor configured to extract difference image data based on first image data read from the sheet before decoloring the image formed by the decolorable ink or the decolorable toner and second image data read from the sheet after decoloring the image formed by the decolorable ink or the decolorable toner; and set a first password to permit access to the difference image data, receive an input of a second password; determine a coincidence between the first password set by the processor and the second password that is received as the input; and generate third image data based on the second image data and the difference image data in response to a determination that the first and second passwords match with each other.
 2. The image decoloring apparatus according to claim 1, wherein the processor is configured to set the first password based on at least one of a color, a character or a figure among the difference image data.
 3. The image decoloring apparatus according to claim 1, wherein the processor is configured to delete the first image data from the memory when the processor extracts the difference image data.
 4. The image decoloring apparatus according to claim 1, wherein the processor is configured to cancel the first password in response to the determination that the first and second passwords match each other.
 5. The image decoloring apparatus according to claim 1, wherein the processor is further configured to generate the third image data based on the second image data and the difference image data, or to generate the third image data based on the second image data and other difference image data, and permit access to the third image data that is based on the second image data and the difference image data after a second password is inputted, or to permit access to the third image data that is based on the second image data and the other difference image data without the second password being inputted.
 6. An image decoloring method, including: conveying a sheet on which an image is formed on a surface thereof; reading the surface of the conveyed sheet, including an image formed by decolorable ink or decolorable toner; acquiring first image data indicative of image data of the image on the sheet before decoloring the image formed by the decolorable ink or the decolorable toner; reading the image on the sheet after decoloring the image formed by the decolorable ink or the decolorable toner; acquiring second image data indicative of image data of the sheet after decoloring the image formed by the decolorable ink or the decolorable toner; extracting difference image data based on the first image data and the second image data; and setting a first password to permit access to the difference image data, receiving an input of a second password; determining a coincidence between the first password and the second password; and generating third image data based on the second image data and the difference image data upon determining that the first and second passwords match with each other.
 7. The image decoloring method according to claim 6, further comprising: setting the first password based on at least one of a color, a character or a figure among the difference image data.
 8. The image decoloring method according to claim 6, further comprising: deleting the first image data from storage upon extracting the difference image data.
 9. The image decoloring method according to claim 6, further comprising: cancelling the first password upon determining that the first and second passwords match each other.
 10. The image decoloring method according to claim 6, further comprising: generating the third image data based on the second image data and the difference image data, or generating the third image data based on the second image data and other difference image data, and permitting access to the third image data that is based on the second image data and the difference image data after a second password is inputted, or permitting access to the third image data that is based on the second image data and the other difference image data without the second password being inputted.
 11. An image decoloring apparatus, comprising: a reader configured to read an image on a sheet, including an image formed by decolorable ink or decolorable toner, to acquire image data; and a controller comprising a processor and a memory, the memory being configured to store the image data acquired by the reader and being further configured to store at least one control program which, when executed by the processor, causes the controller to perform operations including: extracting difference image data based on first image data read from the sheet before decoloring the image formed by the decolorable ink or the decolorable toner and second image data read from the sheet after decoloring the image formed by the decolorable ink or the decolorable toner; and setting a first password to permit access to the difference image data, receiving an input of a second password; determining a coincidence between the first password and the second password; and generating third image data based on the second image data and the difference image data upon determining that the first and second passwords match with each other. 